Energy storage for a green energy economy is a problem that plagues the development of large carbon friendly infrastructure. It is easy to pontificate on the removal of the coal fired generation in this province; it is however, quite another thing to implement.
The wind and solar systems, proposed as the main alternative to coal, lack the obvious advantages of hydroelectricity. Simply put, the output from these sources cannot be easily stored until needed. Unlike a hydro damn with its straightforward energy generation process of letting water flow as required, it’s not that effortless with wind and solar. One solution is to have a number of wind farms in different areas, as the wind generally blows somewhere. Solar, however, is affected by cloud cover and ultimately is shut down by darkness. Mankind’s need for warmth and cooking do not follow the cycles of natural forces. We tend to like consistency in our energy supplies.
The search for technologies to implement storage for wind and solar has been wide ranging. Gravity is being used in California, different forms of battery banks, from lithium ion to lignite solution, are being seriously explored but perhaps the most pioneering and inventive solution, may be the use of a yellow liquid all humans, by necessity, deal with on an hourly basis.
Being one of the most common and familiar materials on earth, urea is the main non-water constituent of urine. Researchers at the University of Bath in England have developed a microbial fuel cell powered by this golden elixir for all things organic. Now researchers at Stanford University, searching for an alternative to an expensive chemical electrolyte mixture, may have come up with a cost efficient alternative using the golden flows of the Kingdom Animalia.
Originally, 1-ethyl-3-methylimidazolium chloride, -EMIC-, was mixed with aluminum chloride to make an ionic salt liquid. This aluminium ion battery was intended for large energy storage systems needed for wind farms and solar arrays. However at over $50 per kilogram the cost was prohibitive. This is where the urea comes into play. At 50 cents per kilogram urea has proven not only to be cost efficient, but when used as a battery it has some very attractive attributes.
The Coulombic efficiency of a urea battery is extraordinary, exceptional even. Coulombic efficiency is defined as the measure of energy output versus the amount of energy input. At 99.7 per cent, the urea electrolyte imparts a very long life cycle to the battery. Although it has only half the energy density of its lithium counterpart, it has a higher charge / discharge rate and being that urea is nonflammable and charges in only 45 minutes, it by far, a more cost effective outsized energy storage medium.
As a basic function, one we think of only when we desperately need a washroom, it’s hard to believe such a simple undertaking of life may one day provide a means of energy storage for keeping us warm and toasty. Other than when it is running down our leg.
Lorne Oja is an energy consultant, power engineer and a partner in a company that installs solar panels, wind turbines and energy control products in Central Alberta. He built his first off-grid home in 2003. Contact him at: lorne@solartechnical.ca.